alarm_handler

An Alarm Handling Process

The alarm handler process is a gen_event event manager
process which receives alarms in the system. This process is not
intended to be a complete alarm handler. It defines a
place to which alarms can be sent. One simple event handler is
installed in the alarm handler at start-up, but users are
encouraged to write and install their own handlers.

The simple event handler sends all alarms as info reports to
the error logger, and saves all of them in a list which can be
passed to a user defined event handler, which may be installed at
a later stage. The list can grow large if many alarms are
generated. So it is a good reason to install a better user defined
handler.

There are functions to set and clear alarms. The format of
alarms are defined by the user. For example, an event handler
for SNMP could be defined, together with an alarm MIB.

The alarm handler is part of the SASL application.

When writing new event handlers for the alarm handler, the
following events must be handled:

{set_alarm, {AlarmId, AlarmDescr}}

This event is generated by
alarm_handler:set_alarm({AlarmId, AlarmDecsr}).

{clear_alarm, AlarmId}

This event is
generated by alarm_handler:clear_alarm(AlarmId).

The default simple handler is called alarm_handler and
it may be exchanged by calling gen_event:swap_handler/3
as gen_event:swap_handler(alarm_handler, {alarm_handler, swap}, {NewHandler, Args}). NewHandler:init({Args, {alarm_handler, Alarms}}) is called. Refer to gen_event(3)
for further details.

Functions

clear_alarm(AlarmId) -> void()

AlarmId = term()

Clears all alarms with id AlarmId.

get_alarms() -> [alarm()]

Returns a list of all active alarms. This function can only
be used when the simple handler is installed.

set_alarm(alarm())

alarm() = {AlarmId, AlarmDescription}

AlarmId = term()

AlarmDescription = term()

Sets an alarm with id AlarmId. This id is used at a
later stage when the alarm is cleared.